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Executive Summary
The concept of Attribute Based Access Control (ABAC) has existed for many years. It represents a point
in the space of logical access control that includes access control lists, role-based access control, and the
ABAC method for providing access based on the evaluation of attributes. Traditionally, access control has
been based on the identity of a user requesting execution of a capability to perform an operation (e.g.,
read) on an object (e.g., a file), either directly, or through predefined attribute types such as roles or
groups assigned to that user. Practitioners have noted that this approach to access control is often
cumbersome to manage given the need to associate capabilities directly to users or their roles or groups. It
has also been noted that the requester qualifiers of identity, groups, and roles are often insufficient in the
expression of real-world access control policies. An alternative is to grant or deny user requests based on
arbitrary attributes of the user and arbitrary attributes of the object, and environment conditions that may
be globally recognized and more relevant to the policies at hand. This approach is often referred to as
ABAC.
In November 2009, the Federal Chief Information Officers Council (Federal CIO Council) published the
Federal Identity, Credential, and Access Management (FICAM) Roadmap and Implementation Plan v1.0
[FEDCIO1],
which provided guidance to federal organizations to evolve their logical access control
architectures to include the evaluation of attributes as a way to enable access within and between
organizations across the Federal enterprise.
In December 2011, the FICAM Roadmap and Implementation
Plan v2.0 [FEDCIO2] took the next step of calling out ABAC as a recommended access control model for
promoting information sharing between diverse and disparate organizations. In December 2012, the
National Strategy for Information Sharing and Safeguarding included a Priority Objective that the Federal
Government should extend and implement the FICAM Roadmap across Federal networks in all security
domains. The U.S. General Services Administration (GSA) and the Federal CIO Council are designated
leads for this Objective, and are preparing an implementation plan.
D
espite the clear guidance to implement the FICAM Roadmap and contextual (risk adaptive) role or
attribute based access control, to date there has not been a comprehensive effort to formally define or
guide the implementation of ABAC within the Federal Government. This document serves a two-fold
purpose. First, it aims to provide Federal agencies with a definition of ABAC and a description of the
functional components of ABAC. Second, it provides planning, design, implementation, and operational
considerations for employing ABAC within an enterprise with the goal of improving information sharing
while maintaining control of that information. This document should not be interpreted as an analysis of
alternatives between ABAC and other access-control capabilities, as it focuses on the challenges of
implementing ABAC rather than on balancing the cost and effectiveness of other capabilities versus
ABAC.
ABAC is a logical access control model
that is distinguishable because it controls access to objects by
evaluating rules against the attributes of entities (subject and object), operations, and the environment
relevant to a request. ABAC systems are capable of enforcing both Discretionary Access Control (DAC)
and Mandatory Access Control (MAC) concepts. ABAC enables precise access control, which allows for
a higher number of discrete inputs into an access control decision, providing a bigger set of possible
combinations of those variables to reflect a larger and more definitive set of possible rules to express
policies.
The access co
ntrol policies that can be implemented in ABAC are limited only by the computational
language and the richness of the available attributes. This flexibility enables the greatest breadth of
subjects to access the greatest breadth of objects without specifying individual relationships between each
subject and each object. For example, a subject is assigned a set of subject attributes upon employment